Effects of oxygen-enriched air on cognitive performance during SCUBA-diving - an open-water study

Backround: Nitrogen narcosis impairs cognitive function, a fact relevant during SCUBA-diving. Oxygen-enriched air (nitrox) became popular in recreational diving, while evidence of its advantages over air is limited. Aim: Compare effects of nitrox28 and air on two psychometric tests.Methods: In this prospective, double-blind, open-water study, 108 advanced divers (38 females) were randomized to an air or a nitrox-group for a 60-min dive to 24m salt water. Breathing gas effects on cognitive performance were assessed during the dive using a short- and long-term memory test and a number connection test.Results: Nitrox28 divers made fewer mistakes only on the long-term memory test (p=0.038). Female divers remembered more items than male divers (p<0.001). There were no significant differences in the number connection test between the groups.Conclusion: Likely owing to the comparatively low N-2 reduction and the conservative dive, beneficial nitrox28 effects to diver performance were moderate but could contribute to diving safety.